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what is the SNR of an ADC whose reference Voltage is 4.096V but the maximum applied actual signal does never exceed +/-20mV. The PGA gain setting is at 4 and the ADC Input referred Noise is 22uV. Should I use 4.096  or 14.14mV or 56.56mV as the signal amplitude for the SNR calculation ?

• Hi Amar,

Welcome to the E2E forum !!!

Please find the SNR calculation formula listed below. The SNR is approximately 56dB with the maximum rms input of 14.14mVrms or (20 mV/√2) and ADC input-referred noise of 22uVrms. The SNR will degrade as your maximum input signal is smaller than the reference voltage.

SNR (dB) = 20log10(Max_RMSSignal/RMS_Noise)

Thanks

-TC

• Thanks. This helps. For all dynamic performance calculations, we use the maximum signal voltage that we actually apply to the device rather than the reference voltage.